Having played both it's honestly a difficult choice... I would say Uncharted comes across as a more impressive game and it naturally garners more support and attention being a PS exclusive made by Naughty Dog. Having said that, ROTTR has better character gameplay, by that I mean you character seems more capable in interacting with the world and her foes. Tomb Raider also has a lot more depth in gamepaly overall with things like character customization, side missions, weapon upgrades, map travelling etc. Uncharted's gameplay hasn't changed all that much with the exception of the grappling hook and some minor enhancements to hand-to-hand combat.
It's a difficult one... I appreciate Uncharted 4 for attention to detail, scale and technical accomplishment but I appreciate ROTTR for gameplay mechanics, depth and overall innovation to the genre. For me they each have their own merits and there is no clear winner. Get both if you can!